U.S. patent number 10,589,278 [Application Number 14/778,550] was granted by the patent office on 2020-03-17 for wear cap for an earth working roll.
This patent grant is currently assigned to ESCO GROUP LLC. The grantee listed for this patent is ESCO Corporation. Invention is credited to Boyan K. Bahnev, Erik L. Johnson, Stephen M. Lafond, Cameron R. Leedham.
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United States Patent |
10,589,278 |
Johnson , et al. |
March 17, 2020 |
Wear cap for an earth working roll
Abstract
A wear cap for use on an earth working roil for mining,
construction and public works machines such as crushers, surface
miners, milling machines and the like includes a working end and a
rear mounting end. The rear mounting end including a pair of top
and bottom rearwardly extending protrusions, a retainer, and a
cavity having side stabilizing surfaces and a top and bottom rail
or groove to support the wear cap on a holder mounted to the earth
working roll.
Inventors: |
Johnson; Erik L. (Edmonton,
CA), Lafond; Stephen M. (Millet, CA),
Leedham; Cameron R. (Portland, OR), Bahnev; Boyan K.
(Edmonton, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
ESCO Corporation |
Portland |
OR |
US |
|
|
Assignee: |
ESCO GROUP LLC (Portland,
OR)
|
Family
ID: |
51581791 |
Appl.
No.: |
14/778,550 |
Filed: |
March 18, 2014 |
PCT
Filed: |
March 18, 2014 |
PCT No.: |
PCT/US2014/031095 |
371(c)(1),(2),(4) Date: |
September 18, 2015 |
PCT
Pub. No.: |
WO2014/153361 |
PCT
Pub. Date: |
September 25, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20160290134 A1 |
Oct 6, 2016 |
|
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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61803043 |
Mar 18, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21C
35/183 (20130101); E02F 9/2825 (20130101); E21C
35/18 (20130101); E21C 25/18 (20130101); E02F
9/2858 (20130101); B02C 4/305 (20130101); B28D
1/188 (20130101); E02F 9/2833 (20130101); E02F
9/2866 (20130101); B02C 2210/02 (20130101) |
Current International
Class: |
E21C
25/18 (20060101); E02F 9/28 (20060101); E21C
35/18 (20060101); E21C 35/183 (20060101); B02C
4/30 (20060101); B28D 1/18 (20060101) |
Field of
Search: |
;241/197,305
;175/327,389 ;299/79.1,112,113 ;37/450-456 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1201428 |
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Dec 1985 |
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SU |
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WO 2004/057117 |
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Jul 2004 |
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WO |
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WO 2007/027639 |
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Mar 2007 |
|
WO |
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WO 2009/089322 |
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Jul 2009 |
|
WO |
|
Primary Examiner: Self; Shelley M
Assistant Examiner: Bapthelus; Smith Oberto
Attorney, Agent or Firm: Anderton; John
Parent Case Text
RELATED APPLICATION
This application claims priority benefits to U.S. Provisional
Patent Application No. 61/803,043 filed Mar. 18, 2013 and entitled
"Wear Cap for an Earth Working Roll," which is incorporated herein
by reference in its entirety.
Claims
The invention claimed is:
1. A wear cap for attachment to a base secured to a driven roll in
an earth working machine, the wear cap comprising: a front end; a
rear end including a cavity with a top surface, a bottom surface,
and sidewalls that opens rearward to receive a seat on the base and
generally corresponds to the shape of the seat; an upper end; a
lower end; and a longitudinal axis extending rearward from the
front end, the cavity includes a plurality of side stabilizing
surfaces on each of the sidewalls, each stabilizing surface axially
extends substantially parallel to the longitudinal axis to engage a
plurality of side stabilizing surfaces on the seat, each said side
stabilizing surface on each of the sidewalls is separated by a
transition surface, and the transition surfaces diverge rearwardly,
and the cavity includes a rail or groove in each of the top and
bottom surfaces, the rails or grooves engage respective top and
bottom rails or grooves on the seat wherein each of the transition
surfaces are closer to the rear end when proximate the upper end
and closer to the front end when proximate the lower end.
2. A wear cap in accordance with claim 1 wherein each of the
transition surfaces are inclined to the longitudinal axis at an
acute angle.
3. A wear cap in accordance with claim 1 wherein top surface the
cavity is curved.
4. A wear cap in accordance with claim 1 wherein the upper end of
the wear cap includes a projection extending rearwardly from the
rear end to fit within a recess in the base.
5. A wear cap in accordance with claim 4 wherein the projection
includes a hole for receiving a retainer through the hole to engage
the base.
6. A wear cap in accordance with claim 1 wherein the rear end of
the wear cap includes a hole for receiving a retainer through the
hole to engage the base.
7. A wear cap assembly for attachment to a driven roll in an earth
working machine, the wear cap assembly comprising: a base having a
forward facing seat, a hole, and a mounting end to be secured to
the roll; a wear cap in accordance with claim 1 being separable
from the base, a retainer to be received in the hole in the wear
cap and the hole in the base to releasable hold the wear cap to the
base.
8. A driven roll for an earth working machine, the driven roll
being generally cylindrical and comprising: a plurality of bases
fixed to the roll, each of the bases having a forward facing seat,
a hole, a recess, and a mounting end to be secured to the roll; a
plurality of wear caps in accordance with claim 1 separable from
each of the bases; and a retainer to be received in the hole in the
wear cap and the hole in the base to releasably hold the wear cap
to the base.
Description
FIELD OF THE INVENTION
The present invention pertains to a cap for an earth-working roll
such as used in a roll crusher, surface miner, underground mining
machines, milling machine and the like.
BACKGROUND OF THE INVENTION
A number of machines involved in mining, construction and public
works use rolls that are driven for the crushing, mining, milling
and the like of earthen materials. These earth working rolls
include an array of wear assemblies to engage the material to be
worked. The assemblies generally include a component with an impact
face that is releasably secured to a base attached to the roll.
These components with the impact face are wear parts that are
replaced after a certain length of use.
As one example, earth working tips can be provided in a roll
crusher for the processing of earthen material in a mining
operation. FIG. 1 shows a double roll crusher 10 including a pair
of opposed rolls 12 to break up the mined material 14. Each roll 12
is fitted with an array of tips 20 configured to impact and
separate the material. The tips are fixed to the roils 12.
Generally, the rolls 12 are rotated in opposite directions so that
the tips 20 are driven toward each other from the top during normal
operation. However, the rolls may be operated in the opposite
direction for clearing the crusher. Additionally the rolls may be
designed so that the tips are driven toward each other at the
bottom of the roll during normal operation. The broken material 14A
passing through the roll crusher is deposited on a conveyor for
transport to additional processing.
This kind of machinery is generally capital equipment and an
important part of the processing operation. Minimizing downtime for
maintenance and refurbishment of wear components is a priority.
With an array of tips, tip replacement can take the equipment out
of service for extended periods.
The tips are close fitting with the bases to provide sufficient
support for the tip. Even so, due to the invasiveness of earthen
fines and the chaotic nature of a crushing or mining operation,
fines commonly get embedded in crevices and openings. The fines
consolidate into a concretion with the consistency like concrete
and bind mated surfaces. Applied force or a cutting torch is often
necessary to separate the components. Hammering and prying of the
components may be required which can result in breakage and
shrapnel from the target components.
SUMMARY OF THE INVENTION
The present invention pertains to an improved wear cap assembly for
use on earth working rolls for mining, construction and public
works machines such as crushers, surface miners, underground mining
machines, milling machines and the like.
Extreme wear associated with the operation of a driven roll is
experienced primarily on the front end of the component striking
the earthen material, and in the primary direction of flow of the
material in the crusher. As a result, this component wears out well
before the other components in the crusher. With this present
construction, only the wear cap needs to be replaced, and
successive wear caps can be mounted onto the same base. By
replacing only the wear cap, less discarded material is generated
and fewer steps are required than replacing a conventional tip for
less equipment downtime. The present construction allows for a cost
effective component. In a preferred construction, the wear caps are
cast without the need to machine the part.
In accordance with one aspect of the invention, the wear cap
assembly comprises a wear cap that engages the earthen material and
a base attached to the roll. The wear cap includes a flange
extending rearwardly that is received into a recess of the base. A
retainer releasably secures the wear cap to the base.
In accordance with another aspect of the invention, the wear cap
assembly includes a wear cap with a cavity for receiving a seat of
the base. The wear cap and seat include rearwardly extending rails
and grooves on top and bottom surfaces to stabilize and securely
hold the wear cap to the base. During operation the wear cap
impacts material at high speed and experiences significant loading.
The grooves receive the rails on assembly and, together with
corresponding side surfaces of the seat and the cavity resist and
absorb side impacts on the wear cap. The corresponding top and
bottom surfaces of the wear cap and the seat resist and absorb
vertical impacts to the wear cap.
Renewing worn wear caps on a driven roll can also be accomplished
easily and quickly without hammering. In a method in accordance
with the present invention a retainer holding the worn cap to the
base is released. Each worn wear cap is separated from the seat of
its base and a wear cap flange is separated from a recess of the
base. A new wear cap receives the seat where the worn wear cap was
removed and the recess receives the flange of the new wear cap.
Each newly installed wear cap is then secured to the seat with a
retainer.
In another aspect of the invention, a single retainer is positioned
in a rearward extension of the wear cap to secure the wear cap onto
the seat of the base. The retainer preferably extends through
threaded and unthreaded portions of the wear cap and the seat
though other arrangements are possible. The retainer is loaded in
shear where it is oriented transversely to the longitudinal axis.
In an alternative embodiment the retainer is oriented along the
longitudinal axis and is loaded in tension to retain the wear cap
to the seat. The retainer acts to limit separation of the wear cap
from the base.
In another aspect of the invention, at least one flange extends
rearwardly from the wear cap and engages a recess of the base. In a
preferred embodiment the flange is straight. In an alternative
embodiment the flange and the recess are both curved. To engage the
flange in the curved recess the end of the flange is positioned at
the opening of the recess. The wear cap is rotated about the axis
of curvature of the flange and recess so the flange advances into
the recess. The upper surface of the seat preferably is curved with
an axis of curvature similar to that of the recess so the cavity of
the wear cap fully seats on the base without interference.
Nevertheless, other shapes are possible to achieve the same
result.
In another aspect of the invention, a retainer on advancing through
the opening preferably takes up the gap between opposing faces of
the seat and the wear cap cavity such as corresponding bottom
surfaces and corresponding thrust faces. Tightening the retainer
increases the preload stress between these surfaces to limit
movement between the wear cap and the seat during operation.
In another aspect of the invention, the wear cap includes a pair of
rearward projections, one along its top surface and one along its
bottom surface. The pair of rearward projections are received in
corresponding recesses or notches in the base for additional
support in resisting the applied loads. In the first embodiment
illustrated herein, one projection is supported on the top and
bottom projection surfaces and the second projection is supported
along opposite sidewalls. The projections could both be supported
along top and bottom surfaces or both supported on side surfaces,
or along the top, bottom and side surfaces. The projections could
be supported in reverse positions from what is illustrated or only
one projection may be provided.
In another aspect of the invention, the wear cap assembly includes
a wear cap with a cavity for receiving a seat of the base. Both the
wear cap and the seat include a pair of side stabilizing surfaces
separated by a transition surface on each sidewall. The use of side
stabilizing surfaces separated by a transition surface on each side
wall provides a stable mounting of the wear cap and enables the
seat to be widened for greater strength.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of the operation of the rolls in
a double roll crusher.
FIG. 2 is a side view of a wear assembly with a wear cap and a base
attached to a roll in accordance with the present invention.
FIG. 3 is a side cross-section view of the wear cap.
FIG. 4 is a side view of the base.
FIG. 4A is a cross section of the seat of the base taken along line
4A-4A in FIG. 4.
FIG. 5 is a rear perspective view of the wear cap.
FIG. 6 is a top view of the wear assembly.
FIG. 7 is a front elevation view of the wear assembly.
FIG. 8 is a front elevation view of the base.
FIG. 9 is a perspective view of the base.
FIG. 10 is a side cross-section view of the wear assembly.
FIG. 11 is a side cross-section view of a detail for the wear
assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention pertains to wear cap assemblies for an earth
working roll or roller such as used in roll crushers, surface
miners, milling machines and the like. The wear caps and assemblies
in this application are described primarily in the context of a
double roll crusher, but the invention is not limited to this
operation. Wear cap assemblies in accordance with the invention are
also suitable for use in conjunction with other earth working
machines involving the use of driven rolls with caps such as single
roll crushers, scroll crushers, surface miners, underground mining
machines, milling machines and the like.
Wear caps are sacrificial components subjected to heavy erosion in
abrasive environments. Typically, an array of 50-120 wear caps may
be installed on a generally cylindrical roll. As shown in FIG. 1,
during normal operation, the rolls 12 are rotated in opposite
directions so that the tips 20 are driven in an arcuate path with
the roll toward each other from the top of the roll. However, the
rolls may be operated in the opposite direction for clearing the
crusher. Additionally the rolls may be designed so that the tips
are driven toward each other at the bottom of the roll during
normal operation. The broken material 14A passing through the roll
crusher is deposited on a conveyor (not shown) for transport to
additional processing. Crushers may be run continuously in a mining
operation and stopped only to replace the wear caps as they are
worn away and/or conduct other maintenance. Minimizing the
equipment downtime required for renewing the crusher with new caps
reduces expenses and increases productivity. The present invention
incorporates a stable mounting system with a single retainer, and
lessens the time required to detach a wear cap from its base. The
retainer preferably pulls the wear cap against a portion of the
base to maintain a positional relationship of the wear cap with the
base during operation. The use of wear caps in accordance with the
preferred embodiment also reduces the cost as compared to
conventional tips by reducing the throw-away material and
eliminating the need to machine a mounting shank. The use of a
diverging cavity to support the wear cap in lieu of a machined
mounting shank in a conventional tip also eases and speeds removal
and renewal of the roll crusher.
Wear assembly 20 includes a wear cap 22 mounted on a base 24 (FIGS.
2-9). Wear cap 22 is preferably a one piece cap with a forward
working end 22A, a rearward mounting end 22B, at least one
rearwardly extending projection or flange 26 and a rearward opening
cavity 30 for receiving a seat 34 on a base 24. Cavity 30 defines a
longitudinal axis 28 extending between the forward working end and
the rearward mounting end generally in the direction of
installation of the wear cap on the seat. Cavity 30 opens in a rear
wall 22C of wear cap 22 and is configured to matingly receive seat
34 to mount wear cap 22 for operation. Cavity 30 and seat 34 are
hidden in FIG. 2 and indicated by dotted lines.
In the illustrated embodiment, base 24 is defined as a holder
securely mounted to roll 12 by welding, mechanical attachment or
cast as part of the roll. Wear assembly 20 is engineered to impact
consolidated material 14 at the working end 22A and separate it
into manageable portions. The generated force of the impact at
working end 22A is transferred through the wear cap, the mounting
end 22B and base 24 to roll 12 with minimal shifting of the
components. Shifting of the wear cap on the base generates excess
heat and excessive wear at the mating surfaces and reduces
efficiency of the machine.
Alternatively, the wear cap can be mounted on a base in the form of
an adapter mounted in a holder secured to the roll. The adapter can
include a seat that is received by the wear cap and the base
receives the adapter to securely mount the wear cap to the roll.
Additional details concerning wear cap assemblies using an adapter
are disclosed in International Publication No. WO2012/142535 which
is incorporated herein by reference in its entirety.
In another alternative, the wear cap can be mounted on a base in
the form of a conventional shank such as disclosed in US Patent
Publication 20090174252 titled "Tip for an Earth Working Roll"
which is incorporated herein by reference in its entirety. This
construction can be beneficial for retrofitting existing
machines.
In one preferred construction, cavity 30 includes upper and lower
surfaces 30A and 30B, side stabilizing surfaces 30C and side
transition surfaces 30D. Side stabilizing surfaces 30C axially
extend substantially parallel to the longitudinal axis for improved
stability and support to resist transverse forces. The term
substantially parallel in this application refers to surfaces that
are parallel to or diverge extending along the longitudinal axis at
an angle of seven degrees or less. The side walls preferably
diverge five degrees or less, and most preferably extend an angle
of 2-3 degrees to the longitudinal axis in the rearward direction.
A slight divergence is preferred for casting of the caps.
Upper and lower bearing surfaces 30A and 30B and side transition
surface 30D face generally inward and rearward from the direction
of rotation R1. Cavity 30 with rearward facing surfaces 30A, 30B
and 30D generally diverges and opens toward rear wall 22C extending
along longitudinal axis 28. Conversely, cavity 30 generally tapers
extending forward. This taper enables easier removal of the wear
cap and permits widening of the seat for strength.
Cavity 30 may also include a rail or groove separate and spaced
from the stabilizing surfaces 30C that engages the other of a
groove or rail on seat 34. In the illustrated embodiment, rail 38A
and 38B are shown as a protrusion from the upper and lower bearing
surfaces 30A and 30B (FIG. 5). The rails 38A and 38B could be
arcuate in transverse cross section or could be defined by planar
surfaces forming a step on the bearing surface. The rails 38A and
38B are shown extending rearward in cavity 30. A rail could be
formed on only one of the upper and lower surfaces 30A and 30B,
along the sidewalls as disclosed in US Patent Publication
20090174252, along at least one of the upper or lower surface 30A,
30B and the sidewalls, or could be omitted entirely.
Base 24 includes a forward seating end 24A, a rearward mounting end
24B and a front wall 24C at seating end 24A (FIGS. 2, 4, and 8).
Seat 34 includes upper and lower bearing surfaces 34A and 34B, side
stabilizing surfaces 34C and transition surfaces 34D to complement
surfaces 30A-D in cavity 30. Side stabilizing surfaces 34C axially
extend substantially parallel to longitudinal axis 28. Upper and
lower surfaces 34A and 34B and transition surface 34D face
generally forward in the direction of, and converging along,
longitudinal axis 28 providing a forward taper to seat 34.
When cavity 30 receives seat 34, corresponding surfaces of cavity
30 and seat 34 are juxtaposed and in opposition. Top and bottom
surfaces 34A and 34B of seat 34 and top surface 30A and bottom
surface 30B of cavity 30 face each other. These surfaces may or may
not bear against each other on assembly. In operation these
surfaces bear against each other to resist and absorb the applied
loads. Front or thrust surface 34F of seat 34 and front or thrust
surface 30F of cavity 30 face each other and side stabilizing
surfaces 34C and side surfaces 30C face each other. In operation
the side surfaces of the seat and cavity bear against each other to
resist and absorb side impacts and loads.
Preferably, the seat and the cavity include front and rear side
stabilizing surfaces 30C and 34C axially extending substantially
parallel to the longitudinal axis to help stabilize the fit of the
wear cap 22 on seat 34 during use. For example, a load that
transmits lateral forces to the wear cap will be resisted (in part)
by the forward side stabilizing surfaces on the side where the
force is applied and the rearward side stabilizing surfaces 30C on
the opposite side. The axial extension substantially parallel to
the longitudinal axis reduces the tendency of the wear caps to be
pushed from the seat. As a result, wear cap movement on the seat is
reduced for less wear and the load on the retainer is reduced.
Side stabilizing surfaces 30C could each be a single surface, but
are preferably separated by transition surfaces 30D to enable
widening of the seat 34 for greater strength. In a preferred
embodiment, the transition surfaces 30D are inclined relative to
the longitudinal axis as they extend between upper bearing surface
30A and lower bearing surface 30B. As seen in FIG. 3, transition
surfaces 30D are proximate rear wall 22C when adjacent upper
bearing surface 30A, and proximate thrust face 30F when adjacent
lower bearing surface 30B. This arrangement of the transition
surfaces 30D provides improved support for the loads as expected
for a roll crushing operation. The transition surfaces 30D,
however, could have a different inclination, a reverse inclination
or no inclination.
Side stabilizing surface 30C may not be in contact with stabilizing
surface 34C when the wear cap is initially installed on the seat,
i.e., there may be a small gap between the side stabilizing
surfaces. This spaced assembly allows for easier manufacturability
by increasing the tolerances between the inter fit pieces. As the
wear cap encounters a force the side stabilizing surfaces of the
seat and cavity bear against each other to resist and absorb the
force. As the tip continues to operate, fines may fill in the gap
between the stabilizing surfaces to lessen the rattle of the wear
cap on the seat. Still, the side stabilizing surfaces 30C and 34C
could be manufactured to be in contact upon initial assembly.
Front wall 24C of the base and rear wall 22C of the wear cap
preferably remain spaced from each other and do not act as bearing
surfaces, i.e., there is a gap between the walls. Transition
surfaces 30D and 34D face each other on assembly. Transition
surfaces 30D and 34D preferably maintain a spaced relationship in
operation and are not intended as primary bearing surfaces to
absorb loads during operation. The spaced surfaces 22C, 24C and
30D, 34D may contact each other during use or could be designed to
contact each other. The side transition surfaces together with the
converging top and bottom surfaces provide for the forward tapering
configuration of the exterior surfaces 36A-E of wear cap 22.
Seat 34 may further include one or more rails or grooves that
engage the other of one or more corresponding grooves or rails in
cavity 30. Top and bottom surfaces 34A and 34B of seat 34 are shown
with grooves 40A and 40B. Grooves 40A and 40B could be arcuate in
transverse cross section or could be defined by planar surfaces
forming a step on top and bottom surfaces 34A and 34B. Grooves 40A
and 40B corresponds to the shape of rail 38 and extends rearward on
seat 34. Grooves 40A and 40B receive rails 38A and 38B on cavity 30
receiving seat 34.
Rails 38A and 38B are preferably formed on the wear cap to add
strength to wear cap 22 and provide for thinner wear cap top and
bottom walls than would be possible without the rails. The rails
38A and 38B of cavity 30 engage the grooves on seat 34 and provide
additional stabilization and side support. The provision of a rail
in the upper surface 30A of cavity 30 also provides a larger base
for a retainer, i.e., more threads in the wear cap for a
transversely oriented retainer or a larger diameter for a retainer
oriented in the direction of the longitudinal axis. Alternatively,
rails could be formed on top and bottom surfaces of the seat for
receipt in complementary grooves in the cavity of the wear cap.
A cross section of seat 34 through transition surfaces 34D will
preferably be substantially "H" shaped, but other configurations
are possible (FIG. 4A), but other shapes are possible. The top
groove 40A forms an indentation on the top surface 34A and the
bottom groove 40B forms an indentation on the bottom surface 34B in
the cross section. The top and bottom surfaces of the seat resist
vertical loads applied to the wear cap though an initial gap is
preferred to ease manufacturing and fit. The grooves accept the
rails of the wear cap that provide strength to the top and bottom
walls of the wear cap and the rails in the grooves resist side
loads during operation.
A projection or flange 26 preferably extends rearward from the
lower surface 30B of cavity 30 and rear wall 22C of wear cap 22.
Flange 26 includes upper and lower bearing surface 26A and 26B.
Base 24 further includes a complementary recess 42 at the seating
end of base 24. Recess 42 is partially defined by bearing surfaces
42A and 42B between which is received flange 26. Upper and lower
recess surfaces 42A and 42B face upper and lower flange surfaces
26A and 26B on assembly of wear cap 22 to seat 34.
Wear cap 22 includes a strike or impact face 36, a front face 36A,
lower face 36B, trailing face 36C and left and right sides 36D and
36E shown in FIGS. 3, 6, and 7. Roll 12 has an operational
direction of rotation R1 and a radial direction away from the
rotational axis R2. Front face 36A and lower face 36B generally
face in the direction R1. Trailing face 36C generally faces away
from direction R1. The strike face is arranged to oppose a strike
face in the opposite roll during rotation to crush the material to
a certain size. The faces generally diverge rearward from the front
face. Impact face 36 and front face 36A make initial contact with
the material as the drum rotates to fracture, separate and reduce
the material to a smaller size. The other secondary faces of the
wear cap including top, bottom and side surfaces generally make a
secondary impact on the target materials.
Materials also impact and wear on base 24 requiring the base to be
replaced periodically, although not as frequently as the wear cap.
Alternatively, a sacrificial shroud (not shown) can be fixed to the
base 24 to limit material impact and wear of the base.
Roll 12 operates at a high speed and the array of assemblies impact
and fractures the target materials with significant force. The
impact deflects material in all directions which impact the side
surfaces and generate transverse forces between the wear cap and
the seat. Deflected materials also impact the bottom and top faces
as well, generating additional vertical forces between the wear cap
and the seat.
Wear cap 22 at rear wall 22C preferably includes a projection or
protrusion 52 at the upper end of cap 22 that extends rearward of
wall 22C. Base 24 has a cooperating recess or notch 54 rearward of
wall 24C configured to receive protrusion 52 when wear cap 22
receives seat 34. Preferably, notch 54 supports at least the sides
of protrusion 52, but in some cases additional benefit may be
achieved in the notch also supporting the top and/or bottom
surfaces of the protrusion (not shown). Protrusion 52 provides
support for opening or hole 44A that passes through top face 36C of
wear cap 22 provides further resistance to applied loads and allows
a retainer 46 in opening 44A to engage opening or hole 44B at a
position farther back on seat 34 and wear cap 22. This more
rearward position for the retainer provides additional leverage in
retaining the wear cap to the seat.
As discussed above, a pair of projections preferably extends from
both the upper and lower ends of wear cap 22. The projection 26
extending from the bottom end of wear cap 22 preferably limits
movement of the wear cap as will be discussed below and the
projection 52 extending from the upper end of wear cap 22 provides
support for hole 44A as discussed above. Although it is preferable
to have the construction described above, it is possible for both
protrusions to limit the movement of the wear cap or for each
protrusion to have a hole for receiving a retainer to secure the
wear cap to the seat. However, there is benefit from having just
one protrusion extending from the upper or lower surfaces of the
cavity. In addition, protrusions may extend from the side surfaces
as disclosed in US Patent Publication 20090174252, from at least
one of the upper or lower surface and the side surfaces, or could
be omitted entirely. In addition one of the protrusions may extend
farther rearward than the other protrusion.
Opening 44A threadedly receives retainer 46 in a direction
generally transverse to the longitudinal axis. Seat 34 includes
opening 44B at upper surface 34A. When wear cap 22 fully receives
seat 34 in cavity 30, cap opening 44A generally aligns with seat
opening 44B. Inserting retainer 46 in opening 44A and turning the
retainer advances the retainer in threaded opening 44A. Retainer 46
advances until the free end extends beyond the upper surface 30A
and advances into cavity 30 and seat opening 44B.
In a preferred embodiment, opening 44B is an unthreaded blind hole
and retainer 46 and/or opening 44B includes a tapered portion. The
tapered portions of the opening and/or retainer facilitate
alignment of the openings 44A and 44B where they are not completely
aligned as the retainer advances. Retainer 46 advances into opening
44B and retains the wear cap to the seat by shear on the retainer
without providing take up to pull the wear cap tightly onto the
seat. In an alternative embodiment, retainer 46 is advanced further
into opening 44B to contact a bottom surface of the opening.
Tightening the retainer against the bottom of the opening biases
the wear cap 22 on the seat 34 so bottom surfaces 30B and 34B bear
against each other and are preloaded.
Alternatively, retainer 46 and opening 44B are configured to bias
the wear cap rearward onto seat 34. Retainer 46 advances a tapered
portion into opening 44B and makes contact with the front surface
of opening 44B. As the retainer advances further into the opening a
wider portion of the retainer makes contact with the front of the
opening and the wear cap is urged rearwardly in relation to the
seat. As the wear cap is biased rearward, the corresponding thrust
faces 30F and 34F and bottom surfaces 30B and 34B bear against each
other. Such take up enable wear parts to be fit tightly together to
reduce wearing and to continue to fit tightly even when wear on a
partially used nose begins to appear. In certain embodiments, a gap
can be formed between front surfaces 30F and 34F.
Alternatively, opening 44B can be threaded and opening 44A
unthreaded. Opening 44A or 44B may include a resilient material to
limit free rotation of the retainer, or other arrangements could be
used to resist loosening such as lock nuts, etc. Retainer 46 can be
a bolt. Retainer 46 may have a frustoconical configuration with
threads on the frustoconical surface such as in U.S. Pat. No.
7,536,811, which is incorporated herein by reference in its
entirety. Alternatively, retainer 46 could use an unthreaded
retention method such as a quarter turn latch or a retention pin
(which typically requires a hammer). Examples of alternative locks
may be found in U.S. Pat. No. 8,469,622 or U.S. patent application
Ser. No. 13/547,353 which are incorporated herein by reference in
their entirety.
While crusher 10 operates predominantly by rotating rolls 12 in a
direction R1, the rolls are operated in the opposite direction for
clearing the crusher. Objects are sometimes introduced into the
operation that cannot be processed by the crusher such as certain
kinds of rock, broken machinery pieces or wear members that have
fallen off excavators. Removing them from the crusher, or clearing
the crusher for maintenance or other operations, often requires
reversing the direction of rotation. During reverse rotation
material infeed is typically suspended, but reverse operation still
generates significant forces on the wear cap that can tend to pull
the wear cap off the seat if not sufficiently supported.
In reverse rotation, base 24 initially impacts target materials
rather than front faces 36 or 36A of the wear cap impacting target
materials as occurs in forward operation. The forward tapering of
exterior surfaces of the wear cap lessen the drag on the wear cap
22, but materials still drag on the top and side surfaces of wear
cap 22 and on rear wall 22C where it intersects with the base.
These drag forces tend to pull the wear cap off the seat. Flange 26
and retainer 46 in opening 44 oppose the extraction forces on the
wear cap during reverse rotation of drum or roll 12 as well as
during normal operation. Flange 26 bears against surface 42B and
with retainer 46 in holes 44A and 44B act to resist the extraction
forces as shear force on the retainer.
Alternatively, seat 34 could make an interference fit with cavity
30. On assembly, the top and bottom surfaces of the seat and the
cavity, which diverge extending rearward, would make contact with
the cavity and seat and act as bearing surfaces. In this
configuration, the thrust faces remain spaced on initial
assembly.
Alternatively, on initial assembly or after a period of operation,
the cap may fit on the base so that the corresponding surfaces may
make contact but are not preloaded to bear on each other. Retainer
46 in opening 44 together with flange 26 in recess 42 then
primarily function to limit movement of wear cap in pulling off or
away from base 24 and seat 34.
Wear caps erode and lose material rapidly in an abrasive
environment and need to be replaced on a regular basis. Previous
systems have a relatively complex retention system with multiple
parts including bolts, adapters and/or components that require
sophisticated machining for close tolerances. On a roll with 100 or
more pick assemblies where the retainers tend to be clogged with
fines, downtime for maintenance and replacement of worn components
can be significantly reduced by using a less complex retention
system. Using a single retainer to stably retain the wear cap to
the base has a significant advantage in reducing machine downtime
during maintenance. In addition, by locating the retainer in a top
surface of the wear cap, the retainer is oriented upward and spaced
outward from the roll to be easily accessed by the user. The
construction of the present invention allows manufacture by a low
cost casting operation without extensive machining for close
tolerances as is required in conventional tips.
FIG. 10 is an alternative configuration of wear assembly 20. Wear
assembly 120 includes a wear cap 122, a base 124, a cavity 130 and
a seat 134 received by cavity 130. In this embodiment, base 124
includes an unthreaded opening 144C that accepts retainer 146A. Cap
122 includes a threaded opening 144D for engaging retainer 146A.
Openings 144C and 144D are parallel to, or generally aligned with
longitudinal axis 128. Although this kind of retainer is shown in a
different construction, it can be used with the first (or other)
embodiments.
Wear assembly 120 preferably includes many of the same features as
wear assembly 20. For example wear assembly 120 preferably includes
rails and grooves on top and bottom surfaces of the cavity and seat
as well as corresponding side surfaces, transition surfaces and
thrust faces.
Retainer 146A preferably includes a head larger than the threaded
portion of the retainer. Once advanced into opening 144D, the head
seats against a surface adjacent to opening 144C of base 124, but
other arrangements are possible. Advancing retainer 146A further
pulls cap 122 tight onto seat 134. Opening 144C may further include
a countersink to accept the head of retainer 146A below the surface
of base 124 to reduce wearing during use.
These are preferred examples of wear assemblies in accordance with
the present invention. Retainer 146A and corresponding opening
configurations can take different forms and have different features
to perform a similar function and still fall within the scope of
this disclosure.
FIG. 10 shows recess 142 and flange 126 configured with
complementary curves such that when complementary curve surfaces
are in contact, they have a common axis of curvature. The axis of
curvature is indicated by AC. Three radii from axis of curvature AC
are shown: Rf for the flange bearing surface 126B, Rr for the
recess lower bearing surface 142B and Rs for the seat upper bearing
surface 134A. While the radii are shown with a common axis of
curvature, each axis may approach axis AC and the surface of the
component may vary from a circular arc to account for variations in
casting and to limit binding of the components on assembly.
Mounting wear cap 122 to base 124 with this configuration requires
first inserting the end of flange 126 in the opening of recess 142.
Wear cap 122 is then rotated about the common axis of the curves of
flange 126 and recess 142.
In order for wear cap 122 to rotate about the common axes onto seat
134, upper bearing surfaces 130A of the wear cap and the upper
bearing surface 134A of the seat 134 may be curved with an axis of
curvature AC approaching that of flange 126 and recess 142. This
allows wear cap 122 to rotate over seat 134 without interference
and set against seat 134 when fully installed. Alternatively, upper
surface 130A may alternatively be flat and extend rearward
diverging from the longitudinal axis such that the wear cap rotates
fully onto seat 134 without interference.
Cavity 130 receives seat 134 and an opening 144C of base 124 aligns
with an opening 144D. Opening 144C is shown as a through hole and
is preferably unthreaded. Opening 144D in wear cap 122 is threaded
so that advancing the retainer through opening 1440 to engage
threads in opening 144D pulls wear cap 122 onto seat 134.
In an alternative embodiment shown in FIG. 11, flange 226 and
recess 242 are preferably curved at upper bearing surfaces 226A and
242A with a common axis of curvature. Lower flange surface 226B
forms an interlocking latch 256 with recess lower surface 242B
proximate to the axis of curvature AC. In this configuration wear
cap 222 would be mounted to base 224 in a similar manner as
discussed for the previous embodiment by rotating wear cap 222
about the common axis of curvature until the cavity bears on the
seat. Once seated, lower bearing surface 226B of flange 226 bears
against lower bearing surface 242B of recess 242 along a direction
generally parallel to the longitudinal axis. This latching flange
and recess provides a positive retention of the lower portion of
wear cap 222 to base 224.
Although preferred embodiments are described above for a two piece
cap assembly, other arrangements in accordance with the invention
are possible. Different aspects of the invention can be used in
isolation to achieve some of the benefits of the invention. For
example, a wide variety of different configurations could be used
to form the cavity, the seat, the external wear surface, or the
retainer and still achieve the benefits of discarding less material
when the wear cap working end is worn out and provide a simpler cap
replacement process.
For example, the wear cap could have a cone shaped exterior.
Further, the front surface of the cap could be curved, pointed or
have shapes and/or orientations other than planar and inclined to
the longitudinal axis. The working end of the wear cap may also be
provided with a carbide or hard material front surface, or with
embedded carbide, ceramic or other wear resistant members, or with
other wear resistant means besides hardfacing.
Although the application primarily discloses the use of caps in
accordance with the present invention in conjunction with a double
roll crusher, such caps could be used in other machines including,
for example a scroll crusher.
The caps are at times described in this application in relative
terms such as upper, lower, front, rear, vertical, horizontal and
the like. These relative directional terms are not essential to the
invention. The orientations of the caps on an earth working roll
change considerably during operation. Accordingly, the use of these
relative terms is not to be limiting of the invention, but rather
to clarify the description.
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